<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>流式</title>
  <meta name="viewport" content="width=device-width, initial-scale=1.0,maximum-scale=1,minimum-scale=1,user-scalable=no">
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    body {
      background-color: #ccc;
    }



    ul {
      list-style: none;
      display: flex;
      height: 100px;
    }

    li {
      flex: 1;
      border: 1px solid #000;
      background-color: aqua;
    }
  </style>
</head>

<body>
  <main>
    <section>
      <ul>
        <li>1</li>
        <li>2</li>
        <li>3</li>
      </ul>
    </section>
  </main>
</body>

</html>